From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com ([192.55.52.93]:11488 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750981AbdARRYF (ORCPT ); Wed, 18 Jan 2017 12:24:05 -0500 Date: Wed, 18 Jan 2017 10:22:16 -0700 From: Ross Zwisler To: willy@bombadil.infradead.org Cc: Ross Zwisler , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [LSF/MM TOPIC] Future direction of DAX Message-ID: <20170118172216.GA20111@linux.intel.com> References: <20170114002008.GA25379@linux.intel.com> <20170118052533.GA18349@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20170118052533.GA18349@bombadil.infradead.org> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Tue, Jan 17, 2017 at 09:25:33PM -0800, willy@bombadil.infradead.org wrote: > On Fri, Jan 13, 2017 at 05:20:08PM -0700, Ross Zwisler wrote: > > We still have a lot of work to do, though, and I'd like to propose a discussion > > around what features people would like to see enabled in the coming year as > > well as what what use cases their customers have that we might not be aware of. > > +1 to the discussion > > > - Jan suggested [2] that we could use the radix tree as a cache to service DAX > > faults without needing to call into the filesystem. Are there any issues > > with this approach, and should we move forward with it as an optimization? > > Ahem. I believe I proposed this at last year's LSFMM. And I sent > patches to start that work. And Dan blocked it. So I'm not terribly > amused to see somebody else given credit for the idea. > > It's not just an optimisation. It's also essential for supporting > filesystems which don't have block devices. I'm aware of at least two > customer demands for this in different domains. > > 1. Embedded uses with NOR flash > 2. Cloud/virt uses with multiple VMs on a single piece of hardware Yea, I didn't mean the full move to having PFNs in the tree, just using the sector number in the radix tree instead of calling into the filesystem. My apologies if you feel I didn't give you proper credit.